It’s long been known that nesting seabirds and mammals don’t mix well. That’s why most species choose islands free of rodents and carnivores to nest. Smaller seabirds and those that nest down burrows are particularly vulnerable. And, if mammals get to those otherwise safe seabird colonies, you can expect the pretty rapid disappearance of the birds – they are either killed and eaten or they just don’t even try and nest. Unwanted species like this are called invasive and you can read all about this well studied issue through some titles below.
Birds On The Edge has covered several successful projects to remove unwanted mammals from seabird sites around the British Isles in Lundy Island, the Isles of Scilly, Calf of Man and the Shiant Isles. In Jersey we believe that mammals currently prevent breeding of storm petrel (they breed in good numbers in Alderney) and Manx shearwater and severely suppress our tiny Atlantic puffin population.
Storm petrel chick calling on the Shiant Isles from RSPB
A storm petrel chick has been recorded calling on the Shiant Isles for the very first time. This is an important step for the Shiant Isles Recovery Project as it’s the first known breeding of these seabirds on the islands. The EU LIFE+ funded project played an artificial call of an adult storm petrel outside the suspected burrow nest site to record the chick’s reply call and confirm its presence.
The project, a partnership between RSPB Scotland, Scottish Natural Heritage and the Nicolson family, the custodians of the islands, has been working over the last four years to make these islands, five miles off the coast of Harris, a safer place for Scotland’s globally threatened seabirds to breed. Island restoration projects such as this one are a key part of helping Scotland’s struggling seabird populations develop resilience to ensure their long term survival.
Storm petrels were not able to breed successfully at the Shiants because of their vulnerability to predation from the islands’ population of invasive non-native black rats. These were eradicated over the winter of 2015/16 and the islands were officially declared free of rats earlier this year.
Following the eradication, the project has been working to attract storm petrels to breed on the islands as it has ideal habitat for their nests in the many areas of boulders around the islands. These birds are little bigger than sparrows and only come to land in summer to breed. Scotland’s internationally important population currently nests at only a few offshore islands because of the presence of ground predators at other potential sites.
During the summer of 2017, calling storm petrels were recorded on the Shiants for the first time.
Dr Charlie Main, Senior Project Manager for the Shiant Isles Recovery Project said: “It’s fantastic that this storm petrel chick has been recorded on the Shiants. After the adult was recorded last year we thought it highly likely that they were breeding so to have this confirmed now is great for the project and for the species in Scotland. It’s also another vital step for making these islands a safer place for Scotland’s internationally important seabirds, many of which are struggling to cope with the impact of climate change and a lack of suitable secure breeding sites.
“We’ve strong hopes for the future that more storm petrels will breed here and a colony will be established. Three other calling adults were recorded this summer suggesting that there may have been more breeding attempts. This one chick is incredibly special to everyone who has been involved in the project since 2014; it means that all the work we’ve been doing to make and keep these islands free of invasive predators is paying off. It also shows just how quickly island restoration can make a difference to seabirds which is really positive for future projects like this one.”
And in Jersey?
In 2017, Kirsty Swinnerton, with Piers Sangan, undertook a preliminary review of the conditions available for nesting seabirds on Jersey’s north coast for Birds On The Edge. Kirsty’s report is now available here.
The recent establishment of the Jersey National Park and the acquisition of land at Plémont by the National Trust for Jersey has created some unique opportunities for seabird and habitat restoration. Historically, the north-west coast from La Tête de Plémont to Douët de la Mer supported 200-300 breeding pairs of Atlantic puffin but which have dwindled today to less than 10 pairs at most. The decline has probably been a result of an overall decline in the species’ southern range combined with the impacts of invasive species on Jersey including the brown rat, feral polecat/ferret, European hedgehog, European rabbit, and free ranging/feral cats. In addition, domestic dogs and agricultural stock (sheep and cows) could also prevent the re-establishment of puffins if not carefully managed at seabird nesting sites.
The report provides an overview of existing seabird recovery tools proven to re-establish breeding seabird colonies around the world. The primary focus is on the control of invasive vertebrates to increase the size and distribution of breeding colonies and reproductive success, and on hands-on species recovery techniques used to encourage seabirds to recolonise the area. However, during the study, it became apparent that much of the potential seabird recovery area does not support suitable habitat for puffins or other ground-nesting seabirds. The sites are choked with dense stands of bracken, and this may be the primary factor currently limiting colony growth of puffins and other burrow-nesting seabirds.
To understand more fully the impacts and interactions of invasive species, lack of suitable breeding habitat, and human disturbance on puffin colony re-establishment, the study recommended a pilot project combining species recovery techniques with research and monitoring. It further recommends initial small steps to maximise opportunities for feedback into recovery project development and the development of Species Action Plans for puffins and other seabirds by working groups in order to guide recovery efforts to include local seabird experts and stakeholders, and ensure best practices.
Download Kirsty’s full report Options for the recovery of nesting seabirds on Jersey, Channel Islands
Further reading on invasive mammals and seabirds:
Invasive mammal eradication on islands results in substantial conservation gains (2016)
Invasive predators and global biodiversity loss (2016)
Underlying impacts of invasive cats on islands: not only a question of predation (2014)
Severity of the Effects of Invasive Rats on Seabirds: A Global Review (2008)
Influences on recovery of seabirds on islands where invasive predators have been eradicated,with a focus on Procellariiformes (2016)